Boring bar



Oct. 29, 1957 E. A. ZEMPEL 2,811,055

BORING BAR Filed Aug. 10, 1955 2 Sheets-Sheet 1 INVENTOR EDWARD A. ZEMPEL ATTORNEYS Oct. 29, 1957 Filed Aug. 10, 1955 ZEMPEL BORING BAR 2 Sheets-$heet 2 INVENTOR EDWARD A.ZEMPEL ATTORNEYS United States Patent BORING BAR Edward A. Zempel, Milwaukee, Wis.

Application August 10, 1955, Serial No. 527,516

3 Claims. (Cl. 77-58) This invention appertains to cutting tools, and more particularly to a combination boring bar and finishing tool.

It is customary to provide a boring bar for rough or preliminary work and a separate tool (reamer) for finishing or sizing holes. Usually the bars or shanks of these tools are of different lengths, which is objectionable to the operator of the lathe or like metal working machine, and obviously, the use of two different characters of tools is costly and requires additional time on the part of the operator for mounting, setting, etc.

It is, therefore, one of the primary objects of my present invention to provide a boring bar in which the cutters are provided with a micrometer adjustment for accuracy and one in which the cutters can be locked solid with the bar for boring and released for limited floating movement diametrically in the bar as a unit for finishing or sizing.

Another salient object of my invention is the provision of means whereby round cutters can be effectively used in the bar with releasable means for binding the cutters on their micrometer adjusting screw, so that the cutters will be effectively held to a desired setting after accurate adjustment.

A further object of my invention is the provision of a key block for rotatably supporting the micrometer screw and 'for guiding the cutters during adjustment and for preventing turning of the cutters in the bar, with novel means for mounting the key block in the bar, whereby the same can be correctly centered and locked in the bar against movement so that the cutters can be used for boring or released, so that the cutters and key block will have limited movement diametrically of the bar for self-centering to permit the eifective use of the tool for finishing.

With these and other objects in view, the invention consists in the novel construction, arrangement and formation of parts, as will hereinafter more specifically be described and claimed, and illustrated in the accompanying drawings, in which drawings:

Figure l is a fragmentary central longitudinal sectional view through my improved tool, the section being taken on the line 11 of Figure 2, looking in the direction of the arrows, the view showing the cutters locked solid on the bar for boring;

Figure 2 is a fragmentary side elevational view of the boring bar;

Figure 3 is a fragmentary longitudinal sectional view taken at right angles to Figure 1 and on the line 3-3 of Figure 1, looking in the direction of the arrows;

Figure 4 is a transverse sectional view through the tool taken on the line 44 of Figure 1 looking in the direction of the arrows, the view showing in detail the micrometer adjustment for the cutters;

Figure 5 is a fragmentary longitudinal sectional view through the forward end of the bar taken on the line 2,811,055 Patented Oct. 29, 1957 2 5 -5 of Figure llooking in the direction of the arrows, and

Figure 6 is a transverse sectional view through the tool taken on the line 6-6 of Figure 1, looking in the direction of the arrows and illustrating the means employed for binding the cutters on the micrometer screw against movement. 1

Referring to the drawings in detail, wherein similar reference characters designate corresponding parts throughout the several views, the letter T indicates my improved tool and the same includes a bar 10 having formed therein adjacent to its forward end a diametrically extending round hole 11 which opens out through the opposite sides of the bar. Communicating with-the hole 11 is a front slot 12 the purpose of which will later appear. On the opposite side of the hole 11 from the slot 12 is a rear slot 13, and this slot also communicates with the hole 11 and extends inwardly of the bar from the hole. The slot 13 is provided with a pair of stepped abutment shoulders 14and 15.

Mounted in the hole 11 for sliding movement are like cutters 16 and '17., The cutters are of a substantially cylindrical shape and their outer'ends are formed to provide the desired cutting edges 18. If desired, the cutters can be provided withcarbide cutting tips 19. Each cutter is *provided with an internally threaded socket 20 which extends from its inner end short of its outer end, and when the cutters are mounted in longitudinal alignment for placement in the hole 11, the same are connected by a double ended micrometer adjustment screw 21. One end of the screw is provided with lefthand threads and the other end of the screw is provided with righthand threads, and this screw is threaded into the threaded sockets 20 formed in the cutters. The central part of the screw between its oppositely threaded ends is provided with a smooth bearing portion 22 and flanges 23 are formed on the screw at the opposite ends of said bearing portion. One end of the micrometer adjustment screw 20 is provided with a polygonal shaped socket 24 for the reception of a wrench, whereby the screw can be rotated for adjusting the cutters toward and' away from one another. Each cutter is :provided with a longitudinally extending keyway 25 and these keyways extend outwardly from the inner ends of the cutters short of the outer ends of the cutters. The keyway in one cutter, say cutter 16, has formedin its bottom.

wall a longitudinally extending groove 26, and this groove terminates short of the opposite ends of its cutter. The purposes of the keyways 25 and the groove 26 will later appear. The outer surface of the cutters on the opgFitte'dgwithin the. slot is is a key block 29 and this block includes a forwardly extending centrally disposed yoke 30 which receives the smooth bearing portion 22 of the micrometer screw 20 and this yoke forms a bearing for rotatably supporting the screw. It is to be also noted that the flanges 23 on the screw 20 abut the opposite sides of the yoke. The key block 29 also includes a rearwardly extending centrally disposed tongue 31, one edge of which is located adjacent to the shoulder 14. The key block 29 adjacent to one end thereof carries a stop pm 32 which is adapted to fit in the groove 26 in the cutter 16. The forward edges of the key block are re ceived m the keyways or slots 25 formed in the cutters, and hence the cutters, during their adjustment by the screw 20, slide on the block and the block prevents rotation of the cutters relative to the bar. The pin 32 limits the outward adjustment of the cutters.

the outer op- In actual practice the cutters, the micrometer screw and the key block are assembled as a unit and are then fitted in the bar. In order to hold the assembly in place on the bar, a fastening block 33 is fitted against the shoulder 15 and is secured to the bar by a machine screw 34. The fastening block 33 projects forwardly toward the key block 29 and overlaps the tongue 31 thereof. The fastening block 33 and the bar on its side directly opposite the holding block carry, respectively, screws 35 and 36 which engage the opposite sides of the tongue 31. By adjusting the screws 35 and 36 relative to one another, the key block can be accurately centered in the bar and the key block and the cutters are firmly secured to the bar against movement. In this instance the bar is employed for its usual function of boring.

In order to take up any movement of the cutters on the adjusting screw and so that a desired adjustment of the cutters can be accurately held, I employ a resilient lock plate 37 which is snugly fitted within the slot 12 in the bar. This lock plate 37 engages the fiat surfaces 27 of the cutters. A holding pin 38 is placed through the bar and into the central part of the lock plate 37, and this lock plate at the point of its connection with the holding pin is slotted as at 39 transversely to increase the resiliency thereof and to allow the lock plate to flex at a central point. Threaded into the bar on opposite sides of the holding pin 38 are adjusting screws 40 and 41. The inner terminals of these adjusting screws are pointed and engage wedge surfaces 42 formed in the forward face of the lock plate 37. By adjusting the screws 40 and 41 inwardly, the lock plate can be flexed and pressure will be brought to bear on the slitted cutters for contracting the cutters on their adjusting micrometer screw 20, whereby all lost motion between the cutters and their adjusting screw will be prevented.

When it is desired to use the tool for finishing or sizing holes, the adjusting screws 35 and 36 for the key block are loosened and the screws 40 and 41 for the lock plate are loosened. This allows limited motion of the key block and the cutters diametrically of the bar, and hence the cutters can float inthe bar as a unit and conform themselves to the bored opening in the work.

From the foregoing description, it can be seen that I have provided an exceptionally simple tool which will effectively perform either a boring operation or a finishing or sizing operation.

Changes in detail may be made without departing from the spirit or the scope of my invention, but what I claim as new is:

1. A combination boring and finishing tool comprising a bar having a diametrically extending round opening therethrough and a slot communicating with said opening, cutters of a circular shape in cross section fitted in said opening, the inner ends of said cutters having inte'rnally threaded sockets, a micrometer adjusting screw having right and lefthand threads fitted in said sockets and said screw having a central bearing portion and flanges at the ends of said bearing portions, a key block fitted in said slot having a forwardly projecting yoke receiving the bearing portion of the screw and engaging said flanges, and said cutters having keyways receiving the forward end of the key block on opposite sides of the yoke, and adjusting screws on opposite sides of the bar for movement into and out of engagement with the key block, whereby the block can be held solid in the bar or for limited movement in the bar.

2. A combination boring and finishing tool comprising a bar having a diametrically extending round hole therethrough and a slot communicating with said hole, cutters of a circular shape in cross section fitted in said hole and having internally threaded sockets, a double ended micrometer screw having right and lefthanded threads fitted in the sockets and provided with an intermediate bearing portion and flanges at the ends of said bearing portion, said cutters being provided with longitudinally extending keyways, a key block fitted in the slot and engaging in said keyways and having a forwardly extending yoke rotatably receiving the bearing portion of the micrometer screw and engaging the flanges, said slot being provided with stepped shoulders, said key block having a rearwardly projecting tongue disposed adjacent to one of said shoulders, a fastening block secured to the other of said shoulders and overlappingthe tongue, and adjusting screws carried respectively by the bar and said holding block engaging the opposite sides of the tongue.

3. A boring tool comprising a bar having a diametrically extending round hole therethrough and a slot communicating with said hole, cutters of a circular shape in cross section fitted in said hole having flat portions facing said slot, the inner ends of said cutters being provided with internally threaded sockets, a double ended micrometer screw fitted in said sockets and connecting said cutters, said screw having right and lefthand threads, means in said bar rotatably supporting the screw, said cutters being slit longitudinally with the slits extending from the inner ends thereof short of the outer ends thereof, and means for contracting the cutters on the screw including a resilient plate fittejd in said slot and engaging the flat portions of the cutters, a pin extending into the bar and the central portion of the plate holding said plate in said bar and said plate being slitted transversely at its center to increase the flexibility thereof, and said plate on opposite sides of the pin having wedge faces, and pointed adjusting screws threaded in the bar engaging said wedge surfaces for flexing the bar on the pin against said fiat portions of the cutters.

References Cited in the file of this patent UNITED STATES PATENTS 1,389,492 Davie r Aug. 30, 1921 FOREIGN PATENTS 643,317 Great Britain Sept. 15, 1950 

